Support passing generator objects through the args array in OSR

Only gets hit when there are >=3 !is_defined names also set (other
fake names might also count towards this).

src/codegen/irgen.cpp

@@ -402,6 +402,8 @@ static void emitBBs(IRGenState* irstate, TypeAnalysis* types, const OSREntryDesc
                     ptr = entry_emitter->getBuilder()->CreateBitCast(ptr, BOOL->llvmType()->getPointerTo());
                 } else if (p.second == FLOAT) {
                     ptr = entry_emitter->getBuilder()->CreateBitCast(ptr, g.double_->getPointerTo());
+                } else if (p.second == GENERATOR) {
+                    ptr = entry_emitter->getBuilder()->CreateBitCast(ptr, g.llvm_generator_type_ptr->getPointerTo());
                 } else {
                     assert(p.second->llvmType() == g.llvm_value_type_ptr);
                 }

src/runtime/generator.cpp

@@ -196,7 +196,7 @@ extern "C" BoxedGenerator::BoxedGenerator(BoxedFunctionBase* function, Box* arg1
     void* initial_stack_limit = (void*)(stack_high - INITIAL_STACK_SIZE);
     void* p = mmap(initial_stack_limit, INITIAL_STACK_SIZE, PROT_READ | PROT_WRITE,
                    MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS | MAP_GROWSDOWN, -1, 0);
-    assert(p == initial_stack_limit);
+    ASSERT(p == initial_stack_limit, "%p %s", p, strerror(errno));
 
     context.uc_stack.ss_sp = initial_stack_limit;
     context.uc_stack.ss_size = INITIAL_STACK_SIZE;

test/tests/generator_osr.py

@@ -7,3 +7,45 @@ def f(x):
 
 print list(f(5))
 
+# Reduced form of the 'permutations' test:
+def f2(x):
+    if 0:
+        a, b, c, d, e = range(5)
+    for i in xrange(20000):
+        pass
+    yield x
+    if 0:
+        print a, b, c, d, e
+print list(f2(5))
+
+
+# Regression test taken from bm_ai.py:
+# Pure-Python implementation of itertools.permutations().
+def permutations(iterable, r=None):
+    """permutations(range(3), 2) --> (0,1) (0,2) (1,0) (1,2) (2,0) (2,1)"""
+    pool = tuple(iterable)
+    n = len(pool)
+    if r is None:
+        r = n
+    indices = range(n)
+    cycles = range(n-r+1, n+1)[::-1]
+    yield tuple(pool[i] for i in indices[:r])
+    while n:
+        for i in reversed(range(r)):
+            cycles[i] -= 1
+            if cycles[i] == 0:
+                indices[i:] = indices[i+1:] + indices[i:i+1]
+                cycles[i] = n - i
+            else:
+                j = cycles[i]
+                indices[i], indices[-j] = indices[-j], indices[i]
+                yield tuple(pool[i] for i in indices[:r])
+                break
+        else:
+            return
+
+t = 0
+for p in permutations(range(10), 3):
+    t += 1
+print t
+